Disc brake with homogeneous brake stack

ABSTRACT

A lightweight disc brake utilizing homogeneous brake discs to provide heat absorbing characteristics superior to steel. The brake discs are made from graphite and/or carbon materials where the graphite and/or carbon acts as the primary heat sink and with the graphite-carbon disc itself acting as the basic friction material. The discs are preferably in the shape of flat annular rings. Straps may be utilized in a segmented design or to reinforce drive lugs for torque transmittal. Strengthening and anti-oxidizing agents can be added to the discs.



1. A disc brake which comprises; a rotatable body, a fixed axle rotatably supporting the body, a stack of discs in the earth''s atmosphere each having portions splined in aligned alternating relation respectively to the axle and the body, each disc characterized by being made from a carbon base material having low weight, high specific heat, and low thermal expansion properties, and having a friction coefficient of at least 0.10 between adjacent discs over the normal operating temperature range thereof, and reinforcing means strengthening the splined portion of each disc so that each disc is capable of transmitting torque regardless of the direction of rotation of the disc.
 2. An annular brake disc having high heat sink, strength, and friction properties which is characterized by being made from a carbon base material to provide a friction coefficient of at least 0.1 when in engagement with a similar disc in the earth''s atmosphere, where the specific heat is at least 0.17 cal./gm./* C., and the density is greater than 1.45 grams per cubic centimeter, but less than 2.5 grams per cubic centimeter, and which includes notches therein to receive splines to achieve transfer of torque, and where the notches have parallel sides and withstand 5,000 p.s.i. for extended periods of time and 15,000 p.s.i. for short high peak loading periods of time, and a metallic strap insert attached to the disc to extend across and strengthening each notch.
 3. A disc brake which comprises: a rotatable body, a fixed axle rotatably supporting the body, a stack of discs associated with the axle and body in a gaseous atmosphere, each disc characterized by being made from a carbon base material having low weight, high specific heat, and low thermal expansion properties, and having a friction coefficient of at least 0.10 between adjacent discs over the normal operating temperature range thereof, reinforcing means strengthening and defining a plurality of splined portions for each disc so that each disc is splined in alternating relation respectively to the axle and the body and is capable of transmitting torque regardless of the direction of rotation of the body, and means to press the discs together.
 4. A disc brake which comprises a rotatable body substantially open to a gaseous atmosphere, a fixed axle rotatably supporting the body, a stack of discs splined in alternating relation respectively to the axle and the body, and means to press the discs together which is characterized by each disc being made from a carbon-based material of substantially uniform composition in cross section having low weight, high specific heat and low thermal expansion properties, and having a friction coefficient of at least 0.10 between adjacent discs over the normal temperature operating range thereof.
 5. A disc brake according to claim 1 where high temperature strengthening agents from a group including tungsten, and silicon carbide are added so as to comprise less than 25 percent by volume of the discs, and which includes an anti-oxidizing coating covering all non-rubbed portions of each disc which is from a group of materials comprising electrolysis nickel and electro-plated chrome; electro-plated nickel and chrome flash; chromium and chromium oxide; silicon carbide; silicon metal; electro-plated nickel over copper; and electro-plated cadmium over nickel.
 6. A disc brake according to claim 5 where the discs are slotted to provide the splined relationship with the axle and body and where the clearances of the slots to the splines is less than 0.25 inches, and where the anti-oxidizing additive is a thin coating covering the non-rubbed surface of the disc.
 7. A disc brake according to claim 6 where there are at least four slots in the discs and where each slot will have torque loading with a respective spline of the axle or body less than 5, 000 p.s.i. for normal service operation, and torque loading of less than 15,000 p.s.i. for short time peak requirements.
 8. A disc brake according to claim 7 which includes notches therein to receive splines to achieve torque transfer of torque, and where the notches have parallel sides and each notch will carry 5,000 p.s.i. for extended periods of time and 15,000 p.s.i. for short high peak loading periods of time, and the notches have a clearance of between 0.010 and 0.004 inches with the splines, and where the brake discs have a flexural strength greater than 5,000 p.s.i., a density greater than 1.45 grams per cubic centimeter, a specific heat of at least 0.17 cal./gm./* C., and a heat conductivity of greater than 0.04 calories per second per square centimeter per centimeter per degree centigrade.
 9. An annular brake disc having high heat sink, strength and friction properties, comprising: an annular disc of a carbon based material having torque transmitting means on one circumference thereof for engagement with complementary torque transmitting means, said means capable of transmitting torque regardless of the direction of rotation of the disc; metallic reinforcing means strengthening the torque transmitting means of the disc, said reinforcing means having a center portion whose configuration is complementary with that of the transmitting means and fully overlying the transmitting means, said reinforcing means also having tabs extending from the center portion of the reinforcing means, the tabs overlying the sides of the disc along the circumference thereof adjacent to the transmitting means; and means securing the tabs of the reinforcing means to the disc.
 10. The annular brake disc according to claim 9 wherein the torque transmitting means of the disc comprise lugs projecting from one circumference of the disc to be received in torque transmitting grooves, the center portions of the reinforcing means covering the sides and extending over the central portions of the lugs.
 11. A disc brake which comprises: a rotatable body, a fixed axle rotatably supporting the body, a stack of discs in a gaseous atmosphere each having portions splined in aligned alternating relation respectively to the axle and the body, each disc characterized by being made from a carbon base material having low weight, high specific heat, and low thermal expansion properties, and having a friction coefficient of at least 0.10 between adjacent discs over the normal operating temperature range thereof, reinforcing means strengthening the splined portion of each disc so that each disc is capable of transmitting torque regardless of the direction of rotation of the body, and means to press the discs together.
 12. A disc brake according to claim 11 which includes an additive to the carbon base material making up each disc to help prevent oxidation of the discs during use.
 13. A disc brake according to claim 12 which includes high temperature strengthening agents from a group including tungsten and silicon carbide added so as to comprise less than 25 percent by volume of the discs, and the anti-oxidizing agents are selected from a group consisting of boron, tungsten, silicon carbide, zirconium, and titanium.
 14. An annular brake disc having high heat sinK and friction properties and being lightweight which is characterized by being made from a carbon base material to provide a friction coefficient of at least 0.1 when in engagement with a similar disc in a gaseous atmosphere, where the specific heat is at least 0.17 cal./gm./* C. across the normal operating temperature range of the disc, and which includes portions therein to receive splines to achieve transfer of torque, and where the portions can withstand 5,000 p.s.i. for extended periods of time and 15,000 p.s.i. for short high peak loading periods of time, and individual reinforcing means attached to the disc to extend across and strengthen each portion for torque transfer regardless of the direction of rotation of the disc.
 15. The annular brake disc according to claim 14 wherein the torque transmitting portions of the disc comprise notches in one circumference of the disc to receive torque transmitting splines, the center portions of the reinforcing means covering the sides and bottom of the notch.
 16. The annular brake disc according to claim 14 further including metallic straps extending along the circumference of the disc between adjacent reinforcing means, the straps overlying a portion of the reinforcing means, and means securing to the metallic straps to the reinforcing means and to the disc.
 17. The annular brake disc according to claim 14 wherein the torque transmitting portions of the disc comprise lugs projecting from one circumference of the disc to be received in splined relation in torque transmitting grooves, the center portions of the reinforcing means covering the sides and extending over the central portions of the lugs.
 18. The annular brake disc according to claim 17 wherein the lugs each consist of a metallic member secured to the center portion of the reinforcing members.
 19. A disc according to claim 14 having the carbon base makes up at least about 75 percent of the volume of the disc, and where the reinforcing means is a stamped metallic insert and riveted into position on the outer periphery of the disc a distance on each side of each notch at least equal to the length of the notch.
 20. A disc according to claim 19 where the disc is divided into a plurality of arcuate segments held in adjacent relation butted at their ends by the metallic insert for each notch. 